This invention relates in general to inertial arresting devices and in particular to a device for bringing a free-falling object to a full stop on a fixed surface without having it bounce up from the surface. More specifically, this invention relates to a device for arresting a succession of falling integrated circuits which may be of nonuniform size and mass at a retention site in order to facilitate such operations as the attachment of test circuit contacts to each integrated circuit with accuracy and at a high repitition rate.
In the manufacture of integrated circuits (IC's) and the like it is highly desirable to test each IC for device performance. However, production economics require that the tests be performed extremely rapidly, a desirable rate being in excess of 5,000 IC's per hour. Apparatus for automatically handling and sorting IC's at these rates are well known in the art. However, to be commercially feasible, such automatic test handlers/sorters must also produce highly reliable tests and be capable of successively processing IC's having different sizes and masses (weights).
It has been found that the most effective design for the IC handling and feeding mechanisms of these apparatus utilizes a vertically oriented gravity feed arrangement that readily accommodates IC's of varying size and mass. It has also been found, however, that this arrangement results in tests that are unreliable. When the vertically falling IC's strike a fixed surface that locates them at the test site, they bounce up from the surface and cause the test circuit contacts to make a poor electrical connection with the IC, completely fail to attach to a designated pin of the IC, or attach to the wrong pin. Simply waiting for the bouncing motion to stop is not a practical solution since it lowers the rate of operation of the testing unit to a commercially unacceptable level. The use of a springloaded device to cushion the landing is likewise commercially impractical since the effect of the spring varies with the mass of the IC it acts upon. For example, if the spring is selected to break the fall of a light IC, a heavier IC nevertheless bounces on impact. Conversely, if the spring is selected for a heavy IC, a light IC does not have a sufficient momentum to reach the desired testing location.
It is therefore a principal object of this invention to provide an inertial arresting device for suddenly bringing a falling integrated circuit or the like to a complete stop on a fixed surface without allowing it to bounce up from the surface.
Another object of this invention is to provide an inertial arresting device that operates in such a manner, without adjustment, for IC's having a variety of sizes and masses.
Still another object is to provide an inertial arresting device having these characteristics that is rugged, reliable, and has a low cost of manufacture.
Yet another object is to provide such an inertial arresting device that is readily incorporated in conventional integrated circuit test handling and sorting devices.